Det-Tronics C7051B, C UV Flame Detector - Manual (Page 7)

8. The SELECT and TEST/ACCEPT buttons are used
to manually test each detector (see “Checkout
Procedure” section). The SELECT button is used to
sequentially select each detector for test. The
TEST/ACCEPT button is used to activate the manu-
al
oi test in each detector when the controller is in
the bypass mode. When the controller is in the nor-
mal mode, the TEST/ACCEPT button performs an
alarm accept function that can be used to de-acti-
vate an alarm circuit without interrupting zone and
fire logic outputs. (See “Theory of Operation” for
details.)
9. The LAMP TEST button is used to illuminate all
LEDs and digital display segments in order to ver-
ify that they are operational. The lamp test can be
performed in the normal mode, since it has no
effect on the system’s operation.
10. The keylock switch is used to select normal and
test modes and to reset the controller. (See
“Theory of Operation” section.)
Field Wiring Connectors
The R7404 Controller is furnished with a field wiring con-
nector that incorporates pressure type screw terminals
for attaching wires and circuit board edge connectors for
plugging the controller in. Each terminal will accept two,
22 gauge wires. Refer to the “Installation” section for a
detailed description of terminal configurations.
Programming Switches
The R7404 is furnished with four rocker switch assem-
blies that are used to select options such as detectors
connected, time delay, fire logic, controller sensitivity,
master/slave position and latching/non-latching. Refer to
the “Theory of Operation” and “Installation” sections for
a detailed explanation of the programming options. It is
essential that the controller be properly programmed
before applying power to the system.
THEORY OF OPERATION
FIRE DETECTION
When a detector senses ultraviolet (UV) radiation, it gen-
erates a series of voltage pulses and transmits them to
the controller. A counter circuit in the controller samples
the incoming signals (or count rate). In the nuclear sur-
veillance system, two factors are weighed against the
count rate of the detector signals. First, the count rate of
the blinded detector modules must be subtracted from
the incoming count rate of the fire detector modules.
After the nuclear surveillance data value has been sub-
tracted, the new adjusted count rate is compared to a
pre-programmed sensitivity setting. (See “Installation -
Switch Setting Procedure.”) If the adjusted count rate
exceeds the sensitivity setting for a pre-programmed
timer interval, the fire controller’s microprocessor will
generate the following response:
1. The appropriate zone output(s) is energized (solid
state - open collector) and the corresponding
ZONE OUTPUT LED blinks. Each of the four detec-
tor pairs is matched with its own zone output and
ZONE OUTPUT LED.
5 95-8256
RED LEDS
GREEN LEDS
ZONES 5-8
RED LEDS
ZONES 1-4
KEYLOCK SWITCH
LAMP TEST
DETECTOR TEST/
ALARM ACCEPT
AMBER LED
DETECTOR SELECTION
AMBER LED
GREEN LED
Figure 3—Front Panel - Nuclear Surveillance Controller
0 — Keylock switch in RESET position, or external
Inhibit/Reset is activated.
1 — Keylock switch in TEST position.
2 — Reduced detector sensitivity (oi fault), or faulty
wiring.
3 — Spurious detector operation, or high background
radiation.
4 — Low +290 vdc (+290 volt detector supply wire may
be shorted).
5 — High +290 vdc (voltage regulation failure in the 290
volt supply).
6 — Fire (Zones 1-4 only).
7 — Count subtraction lockout.
8 — Controller in count test mode.
9 — Data Link Failure (faulty data transfer).
Table 1—System Status Codes